JP4052848B2 - Mounting method of optical element - Google Patents

Mounting method of optical element Download PDF

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JP4052848B2
JP4052848B2 JP2002038370A JP2002038370A JP4052848B2 JP 4052848 B2 JP4052848 B2 JP 4052848B2 JP 2002038370 A JP2002038370 A JP 2002038370A JP 2002038370 A JP2002038370 A JP 2002038370A JP 4052848 B2 JP4052848 B2 JP 4052848B2
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solder
optical element
electrode
solder connection
connection electrode
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良雄 大関
清 松井
和民 川本
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日本オプネクスト株式会社
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    • H01L2224/15—Structure, shape, material or disposition of the bump connectors after the connecting process
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Description

【０００１】
【発明の属する技術分野】
本発明は、光素子を基板上にフラックスを用いないではんだ接続し、三次元的に高精度位置決めする光素子の実装構造体及び光素子の実装方法に関する。
【０００２】
【従来の技術】
基板上へ光素子の実装は、基板上に形成された光導波路と良好な光結合を確保するために１ミクロン以下の位置精度で高精度に実装する必要がある。高精度位置決め技術は、はんだの表面張力を利用したセルフアライメントによる高精度位置決め構造及び方法が研究、開発されている。この中で一般的なはんだ接続に用いられるフラックスは、はんだ及び電極表面の酸化膜を還元除去するとともに接続部を覆い再酸化を防止することができるので、より良好なセルフアライメントを達成できる。しかし、光素子の実装においてフラックスを用いた場合には、電子回路実装で電気的信頼性等の点で問題とならない残さによる汚染が光伝送の妨害になるという問題があり、はんだ接続後の洗浄が必須となる。所が、はんだ接続後の洗浄は追加の工程が必要となり、新たな装置を必要とするので、高コスト化の原因となる。
【０００３】
そこで、洗浄が不要な工程に関して、フラックスレス接続が開発されている。まず、セルフアライメントを用いた半導体の実装構造体または方法に関連する技術、例えば、電極パターンに関連する技術としては、特開平９−２７５１２３号公報及び特開平１１−１１１７７１号公報に記載の技術があげられる。例えば、特開平１１−１１１７７１号公報には、実装機によるＣＳＰキャリア基板の位置ずれを考慮して、４隅の電極パッドが他の電極パッドよりも大きく、かつ４隅のはんだバンプが他のはんだバンプよりも大きく高く形成したＣＳＰキャリア基板と配線基板とを用いてＣＳＰを実装することで、リフローはんだ付けの際にまずは４隅のはんだバンプのセルフアライメントにより、キャリア基板と配線基板との理想的搭載位置からの大きな位置ずれが修正し、さらに４隅のはんだバンプ以外のはんだバンプのセルフアライメントによりセルフアライメント効果を向上させた構造が示されている。
【０００４】
また、セルフアライメントを用いて光素子の水平精度及び垂直精度を向上させた実装技術として、例えば、特開平５―６０９５２号公報及び特開平７−２３５５６６号公報記載の技術があげられる。例えば、特開平５―６０９５２号公報には、セルフアライメントにより水平方向の位置精度を１ミクロン以下とするためには、はんだ接続高さを概ね３０ミクロン以上とする必要があり、一方で垂直方向の位置精度（光素子の傾き）を１ミクロン以下にするためには、はんだ接続高さを概ね１０ミクロン以下とする必要があり、両方を同時に満たすことができる、はんだ接続高さを得ることは難しいことが示されている。その解決手段として、特開平５−６０９５２号公報には、非導電性膜を用いて形成した凹溝内の基板側電極と光素子の電極とをはんだで接続を行い、水平方向の位置決めはんだの表面張力によるセルフアライメントによって達成し、垂直方向の位置決めは、非導電性膜による台座で支持することで達成することが示されている。
【０００５】
【発明が解決しようとする課題】
上記従来技術においては、４隅の電極パッドが他の電極パッドよりも大きく、かつ４隅のはんだバンプが他のはんだバンプよりも大きく、かつ、高く形成することによって、セルフアライメント効果を向上させているが、このような電極パターン及びはんだ量では、垂直方向の位置決め精度の確保が難しいという問題があった。
また、上記従来技術では、垂直方向の位置決め精度を確保するための非導電性膜のパターンニング工程及び位置決め台の形成工程が必要であり、基板製造工程が複雑、高価になるという問題があった。
【０００６】
本発明の目的は、上記の欠点を解決し、溶融はんだの表面張力のみにより、水平方向及び垂直方向の高精度の位置決めを実現する光素子の実装構造技術を提供することにある。
また、本発明の他の目的は、電極形状及びはんだ量を適正化することにより、垂直方向の位置決め精度と高いセルフアライメント性を実現する光素子の実装構造技術を提供することにある。
【０００７】
【課題を解決するための手段】
本発明の目的を達成するために、第１の発明では、光素子の実装構造体は、光素子上に形成された電極と基板上の光素子の電極に対応する位置に形成された電極とをはんだを用いて接続する光素子の実装構造体であって、該光素子の周辺近傍に設けられた第１のはんだ接続用電極と、光素子の他の部分に配置された第２のはんだ接続用電極を備え、該第１のはんだ接続用電極の電極面積Ｓ１、該第２のはんだ接続用電極の電極面積Ｓ２とすると、Ｓ１＞Ｓ２を満足し、かつ該第１のはんだ接続用電極の平均はんだ高さをＨ１、該第２のはんだ接続用電極の平均はんだ高さをＨ２とした場合、Ｈ１＜Ｈ２を満足する。
【０００８】
第２の発明では、第１の発明において、該第１のはんだ接続用電極の電極幅をＬ１、該第１のはんだ接続用電極と第２のはんだ接続用電極の電極間隔をＬ１２、第２のはんだ接続用電極間の電極間隔をＬ２２とした場合、Ｌ１／２＜Ｌ１２、かつＬ１／２＜Ｌ２２の関係を満足させる。
【０００９】
第３の発明では、光素子の実装方法は、光素子上に形成された電極と基板上の光素子の電極に対応する位置に形成された電極とをはんだを用いて接続する光素子の実装構造体を得るために、該光素子の周辺近傍に第１の面積を持つ第１のはんだ接続用電極を設け、光素子の他の部分に該第１の面積より小さい面積を持つ第２のはんだ接続用電極を設けるステップと、該光素子の電極に対応する該基板の位置に第１のはんだ接続用電極と第２のはんだ接続用電極を設けるステップと、該光素子の該第１のはんだ接続用電極又は該基板の該第１のはんだ接続用電極に供給する平均はんだ高さより、該光素子の該第２のはんだ接続用電極又は該基板の該第２のはんだ接続用電極に供給する平均はんだ高さが高くなるようにはんだを供給するステップと、該基板上に該光素子を所定の位置に位置合わせを行い加圧しながらはんだの融点以下の温度で仮接続するステップと、はんだの融点以上に加熱して溶融したはんだの表面張力を利用して該基板電極に対する該光素子上電極の３次元的な位置決めを行うステップとを備える。
【００１０】
第４の発明では、第３の発明において、該はんだ接続用電極を設けるステップでは、該第１のはんだ接続用電極の電極幅をＬ１、該第１のはんだ接続用電極と第２のはんだ接続用電極の電極間隔をＬ１２、第２のはんだ接続用電極間の電極間隔をＬ２２とした場合、Ｌ１／２＜Ｌ１２、かつＬ１／２＜Ｌ２２の関係を満足させる。
【００１１】
第５の発明では、第３又は４の発明において、該はんだを供給するステップは、該光素子または基板上の該第１のはんだ接続用電極に供給するはんだ幅をＬ３とした場合、該第１のはんだ接続用電極幅Ｌ１との関係がＬ１＞Ｌ３となり、かつ該第２のはんだ接続用電極に供給するはんだ幅Ｌ４と該第２のはんだ接続用電極幅Ｌ２との関係がＬ２≦Ｌ４となり、かつ、該第１のはんだ接続用電極に供給するはんだ高さＨ３と該第２のはんだ接続用電極に供給するはんだ高さＨ４の関係がＨ３≧Ｈ４となるようにはんだを供給する。
【００１２】
第６の発明では、第３、４又は５の発明において、該はんだ融点以上に加熱して溶融したはんだの表面張力を利用して該基板上電極に対する３次元的な位置決めを行うステップを、還元性雰囲気の中で行う。
【００１３】
第７の発明では、第３、４又は５の発明において、仮接続した該光素子と該基板間のはんだ接続用電極にはんだの融点よりも高い沸点を有する有機材料を供給するステップを設ける。
【００１４】
更に、第８の発明では、上記のいずれかの発明において、該光素子または基板上電極へのはんだの供給方法が真空蒸着である。
【００１５】
第９の発明では、第７の発明において、該有機材料は、分子内に少なくとも１個以上の水酸基を有するものである。また、該有機材料は該はんだ接続ステップ後において、残さが残らないように蒸発する。
【００１６】
【発明の実施の形態】
以下、本発明の実施の形態を、実施例を用い、図面を参照して説明する。光素子の実装構造体の電極材料として、例えば、Ｔｉ、Ｐｔ、Ａｕの構成で基板および光素子上に電極が形成され、光素子と基板を接続するためのはんだ材料は、Ａｕ及びＳｎの共晶組成（Ａｕ８０ｗｔ％,Ｓｎ２０ｗｔ％）が一般的に用いられている。本発明の対象としては、これらの構成を含むのはもちろん、他の電極およびはんだ材料を用いた場合にも適用可能である。
【００１７】
図１は本発明による光素子のはんだ接続用電極配置の一実施例を示す平面図および光素子の実装構造体の一実施例を示す断面図であり、図１（ａ）は光素子のはんだ接続用電極配置を示す平面図を、図１（ｂ）は光素子の実装構造体の断面図を示す。図１（ａ）に示すように、光素子１には大きい電極面積Ｓ１を有する円形の第１のはんだ接続用電極３ａと、電極面積Ｓ１より小さい電極面積Ｓ２を有する円形の第２のはんだ接続用電極３ｂとがもうけられている。第１のはんだ接続用電極２ａは光素子１の四隅に設けられ、第２のはんだ接続用電極３ｂはその他の部分に配置されている。
図１（ｂ）に示すように、基板５にも光素子１の電極と対応する位置に電極が設けられている。光素子１の第１のはんだ接続用電極２ａに対向する位置に基板５の第１のはんだ接続用電極２ｂが、第２の接続用電極３ａに対向する位置に基板５の第２のはんだ接続用電極３ｂが設けられている。光素子の実装構造体１０１は光素子１の第１、第２のはんだ接続用電極２ａ、３ａと基板５の第１、第２のはんだ接続用電極２ｂ、３ｂの間をはんだ４で接続している。
【００１８】
本実施例では、光素子１を基板５上に仮固定する、即ち、はんだの融点温度未満にして基板上の電極に光素子の電極を載置する、時に生じる位置ずれの許容量を極力大きくするために、電極面積Ｓ１の第１のはんだ接続用電極２とそれより小さい電極面積Ｓ２の第２のはんだ接続用電極３を設けている。なお、本実施例では、第１、
第２のはんだ接続用電極２、３を円形としているが、必ずしも円形とする必要はなく、四角形、多角形、その他の形状でもよい。
第２のはんだ接続用電極３ａ、３ｂは、第１のはんだ接続用電極２ａ、２ｂと合わせて接続強度を確保するとともに、光素子１の電極パターンが第１のはんだ接続用電極２ａ、２ｂだけの場合に比べて、はんだの表面張力によるセルフアライメント効果をより効果的に発揮させるために設けた小さい円形の電極である。
【００１９】
また、図１（ａ）に示すように、隣の電極上に仮固定または接続されることを防止してより効果的にセルフアライメントによる高精度位置決めを実現するために、光素子１の第１のはんだ接続用電極２ａの電極幅をＬ１、第１のはんだ接続用電極２ａと第２のはんだ接続用電極３ａの電極間隔をＬ１２、電極幅がＬ２である第２のはんだ接続用電極３ａ間の電極間隔をＬ２２とすると、Ｌ１／２＜Ｌ１２、かつＬ１／２＜Ｌ２２の関係が成り立つように電極２ａ、３ａを配置した。このため、第１のはんだ接続用電極２ａと第２のはんだ接続用電極３ａとを設けた光素子１を用いることにより、仮固定時の大きな位置ずれを許容し、かつセルフアライメントによる高い水平精度の実現を達成することができる。
【００２０】
図１（ｂ）は、光素子１の電極パターン２ａ、３ａと対応する位置に、第１のはんだ接続用電極２ｂと第２のはんだ接続用電極３ｂを設けた基板５と光素子１を用いてはんだ接続し、セルフアライメント完了後の光素子の実装構造体１０１を示す。
本実施例では、周辺部に形成された第１のはんだ接続用電極２ａ、２ｂの平均はんだ高さＨ１を第２のはんだ接続用電極３ａ、３ｂの平均はんだ高さＨ２よりも低くなるようにすることで、垂直方向に関して溶融したはんだ４が第１のはんだ接続用電極２ｂで光素子１に対して引張力が働き、第２のはんだ接続用電極３ｂでは押し上げ力が働く。このため、光素子１を中央部では押し上げるような力が働き、一方、周辺部では光素子１を基板５の方向に引張るような力が生じる。この溶融したはんだ４の引張力と圧縮力との力のつり合いにより、供給されたはんだ量にばらつきが生じた場合でも、光素子の垂直方向の精度を安定化させることができる。この場合、図１（ｂ）に示すように、第１のはんだ接続用電極２ａ、２ｂ間のはんだ４ａの端部は内側に凹となり、第２のはんだ接続用電極３ａ、３ｂ間のはんだ４ｂは外側に凸になる。
【００２１】
一方、第１のはんだ接続用電極２ａ、２ｂ間及び第２のはんだ接続用電極３ａ、３ｂの平均はんだ高さを等しくした場合、図２（ａ）に示すように、ぬれの時間差やすべての電極に光素子１を押し上げる力のみが働くことに起因して傾きが発生し、垂直方向の実装精度が得られない場合があることを確認した。この傾きをなくすために、図２（ｂ）に示すように、非導電性膜１５に光素子１を接着することが考えられるが、この場合工程が増えることになるため、好ましくない。なお、図２は従来の光素子の実装構造体の断面図である。
【００２２】
ここで、平均はんだ高さについて説明する。平均はんだ高さは、光素子１側の電極と基板５側の電極を上下面とし、その外形を直線で結んでできる立体の体積が基板４の電極上に供給したはんだの体積と等しくなった時の立体の高さを言う。即ち、平均はんだ高さとは、はんだ接続用電極に供給されるはんだ体積を電極面積で割算した値を言う。
【００２３】
図３は本発明による光素子のはんだ接続用電極配置の他の実施例を示す平面図であり、図３（ａ）は電極の形状が四角形の例を、図３（ｂ）は大きい面積の円形電極と小さい面積の円形電極の他の配置例を、図３（ｃ）は大きい面積の四角形電極と小さい面積の四角形電極の他の配置例を示している。
図３（ａ）には、光素子１上の第１のはんだ接続用電極２ａを四角形とし、第２のはんだ接続用電極３ａを四角形とした場合の例が示されている。図３（ｂ）は、円形の第１のはんだ接続用電極２ａを光素子１の四隅には配置していないが、光素子１の周辺近傍に設けられており、中心（重心）に対して点対称に配置した例を示す。図３（ｃ）は、四角形の第１のはんだ接続用電極２ａを光素子１の四隅には配置していないが、光素子１の周辺近傍に設けられており、中心（重心）に対して点対称に配置された例を示す。光素子１の姿勢安定化のためには、第１のはんだ接続用電極２ａと第２のはんだ接続用電極３ａの配置が光素子１の中心（重心）に対して点対称となるように配置することが望ましい。
【００２４】
図４は本発明による光素子の実装構造体の他の例を示す断面図であり、図４（ａ）は光素子の第２のはんだ接続用電極に対して、基板の第２のはんだ接続用電極を小さくした場合の例を、図４（ｂ）は光素子の第２のはんだ接続用電極に対して、基板の第２のはんだ接続用電極を大きくした場合の例を示す。
図４（ａ）は、光素子１側の第２のはんだ接続用電極２ｃに対して基板５側の第２のはんだ接続用電極２ｄを電極の中心を対称にして小さく設け、基板５上に光素子１を実装した光素子の実装構造体１０２を示す。
図４（ｂ）は、基板５側の第２のはんだ接続用電極２ｆに対して光素子１側の第２のはんだ接続用電極２ｅを電極の中心を対称にして小さく設け、基板５上に光素子１を実装した光素子の実装構造体１０３を示す。本実施例では、姿勢を安定化させることができる。
【００２５】
図５は本発明による光素子の実装構造体の実装工程の一実施例を説明するための断面図である。
まず、図５（ａ）に示すように、基板５上の第１のはんだ接続用電極２ｂと第２のはんだ接続用電極３ｃにはんだ６を供給する。本実施例では、リフロー前のはんだに対して符号６を付して、リフロー後のはんだ４と区別する。ここで、第１のはんだ接続用電極２ｂに供給するはんだ幅Ｌ３と電極幅Ｌ１との関係がＬ１＞Ｌ３、かつ第２のはんだ接続用電極３ｂに供給するはんだ幅Ｌ４と電極幅Ｌ２との関係がＬ２≦Ｌ４となるようにはんだ６を供給して、第１のはんだ接続用電極２ｂ上の平均はんだ高さＨ１と第２のはんだ接続用電極３ｂ上の平均はんだ高さＨ２の関係がＨ１＜Ｈ２となるようにする。また、光素子１のいずれかの電極が隣の電極のはんだ６に仮固定または接続されることを防止するために、基板５の第１のはんだ接続用電極２ｂに供給するはんだ高さＨ３と第２のはんだ接続用電極３ｂに供給するはんだ高さＨ４の関係がＨ１＜Ｈ２の関係が成立する範囲内で、Ｈ３≧Ｈ４となるようにはんだ６を供給することが望ましい。このはんだ６の供給方法に関しては、蒸着、メッキ、プリフォーム等によるものがあり、本発明ではいずれの方法ではんだ６を供給してもよい。
【００２６】
次に、図５（ｂ）に示すように、第１のはんだ接続用電極２ａと第２のはんだ接続用電極３ａをもつ光素子１を基板５上に位置合わせを行い、供給したはんだ６の融点以下の温度で加圧することにより、仮接続を行う。これにより、位置合わせから次の工程のはんだ６の加熱溶融による本接続工程までの位置ずれを防止し、生産性に優れた実装工程を実現する。
次に、はんだ溶融接続時の表面張力を利用したセルフアライメントによる光素子１の高精度位置決めを実現するためには、はんだ溶融時にはんだ表面の酸化膜を除去、またはセルフアライメントを妨げない程度に薄く制御する必要がある。本実施例では、図５（ｃ）、図５（ｄ）、図５（ｅ）に示すように還元性雰囲気７中で加熱溶融することにより、第１のはんだ接続用電極２ａ、２ｂのセルフアライメント効果により位置ずれ量が小さくなり、次に第２のはんだ接続用電極３ａ、３ｂによるセルフアライメント効果により高精度位置決めを実現できる。
その後、冷却しはんだ４を凝固させることにより、図５（ｆ）に示すように、フラックスを用いないため、信頼性に影響を及ぼす残さがなく、後洗浄工程を必要としない清浄な実装構造体を得ることができる。
【００２７】
本発明において、はんだ６の溶融加熱時に酸化膜を還元する方法として、図５に示す還元性雰囲気７中で加熱刷る他に、図６に示すような還元性を有する有機材料８を用いる方法がある。
図６は本発明による光素子の実装構造体の実装工程の他の実施例を説明するための断面図である。図６（ａ）に示すように、基板５の第１のはんだ接続用電極２ｂ、第２のはんだ接続用電極３ｂ上にはんだ４を供給し、図６（ｂ）に示すように、基板５上に光素子１を載置して仮固定する。
次に、図６（ｃ）に示すように、光素子１と基板５の間のはんだ接続用電極２ａ、２ｂ、３ａ、３ｂを覆うように有機材料８を供給する。この有機材料８としては、沸点がはんだ６の融点よりも高く、はんだ溶融時にはんだ表面の酸化膜が還元除去され再酸化が防止された状態に保つような材料を選ぶ。還元性をもつ材料としては、分子内に少なくとも１個以上の水酸基を有するアルコール系の材料が適している。例えば、融点が２７８℃のＡｕ２０ｗｔ％Ｓｎはんだを用いる場合には、有機材料８として、トリエチレングリコール（沸点２８５℃）、テトラエチレングリコール（沸点３１４℃）、ペンタエチレングリコール（沸点３７０℃）を用いることにより、セルフアライメントが妨げられず、基板５上への光素子１の高精度な位置決め実装を実現することができることを確認した。図６（ｃ）、図６（ｄ）、図６（ｅ）に示すように、有機材料８を供給、又は塗布した状態で加熱すると、第１のはんだ接続用電極２ａ、２ｂのセルフアライメント効果により位置ずれ量が小さくなり、次に第２のはんだ接続用電極３ａ、３ｂによるセルフアライメント効果により高精度位置決めを実現できる。また、有機材料８は加熱中に蒸発される。よって、有機材料８は図６（ｆ）に示すように加熱中に蒸発するので、残さとして残ることなく、上記実施例と同様に後洗浄工程は不要である。即ち、昇温速度が速く加熱時間が短くなるほど、より低い沸点の材料を使用し確実に蒸発するようにする必要がある。
【００２８】
図７は本発明による光素子の実装構造体を光導波路基板上に実装した場合の一実施例を示す一部断面側面図及び平面図である。光素子１は活性層１０を有しており、の第１、第２のはんだ接続用電極２ａ、３ａは光導波路基板１３の電極２ｂ、３ｂ上に実装される。また、光導波路基板１３には、光素子１の活性層１０を通過した光が光導波路１１のコア層１２を通過することができるように光導波路１１が取り付けられる。
本実施例を用いることにより、光素子１を基板５上の所定の位置に高精度に位置決めされた実装構造が実現することができる。このため、基板５上の光導波路１１にコア層１２と光素子１の活性層１０とを高精度に位置決めでき、光素子と光導波路との光結合を実現することができる。
【００２９】
以上述べたように、本発明によれば、フラックスや垂直方向位置決め用支持台、高価な実装機を用いることなく、はんだ溶融時の表面張力によるセルフアライメント効果のみで、基板上の所定の位置に光素子を高精度に位置決めすることができ、低コスト化を実現することができる。
【００３０】
【発明の効果】
以上述べたように、本発明によれば、はんだ溶融時の表面張力によるセルフアライメント効果で、基板上の所定の位置に光素子を高精度に位置決めすることができる。
【図面の簡単な説明】
【図１】本発明による光素子のはんだ接続用電極配置の一実施例を示す平面図および光素子の実装構造体の一実施例を示す断面図である。
【図２】従来の光素子の実装構造体の断面図である。
【図３】本発明による光素子のはんだ接続用電極配置の他の実施例を示す平面図である。
【図４】本発明による光素子の実装構造体の他の例を示す断面図である。
【図５】本発明による光素子の実装構造体の実装工程の一実施例を説明するための断面図である。
【図６】本発明による光素子の実装構造体の実装工程の他の実施例を説明するための断面図である。
【図７】図７は本発明による光素子の実装構造体を光導波路基板上に実装した場合の一実施例を示す一部断面側面図及び平面図である。
【符号の説明】
１…光素子、２ａ、２ｂ…第１のはんだ接続用電極、３ａ、３ｂ…第２のはんだ接続用電極、４…リフロー後のはんだ、５…基板、６…リフロー前のはんだ、７…還元性雰囲気、８…有機材料、１０…活性層、１１…光導波路、１２…光導波路のコア層、１３…光導波路基板
１０１、１０２、１０３…光素子の実装構造体。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical element mounting structure and an optical element mounting method in which an optical element is solder-connected on a substrate without using flux and is three-dimensionally positioned with high accuracy.
[0002]
[Prior art]
In order to mount an optical element on a substrate, it is necessary to mount the optical element with high accuracy with a positional accuracy of 1 micron or less in order to ensure good optical coupling with an optical waveguide formed on the substrate. In the high-precision positioning technology, a high-precision positioning structure and method by self-alignment using the surface tension of solder has been researched and developed. Among them, the flux used for general solder connection can reduce and remove the oxide film on the surface of the solder and the electrode and can cover the connection portion to prevent reoxidation, thereby achieving better self-alignment. However, when flux is used in the mounting of optical elements, there is a problem that contamination due to residues that do not pose a problem in terms of electrical reliability in electronic circuit mounting interferes with optical transmission. Is essential. However, cleaning after the solder connection requires an additional process and requires a new device, which increases the cost.
[0003]
Thus, fluxless connections have been developed for processes that do not require cleaning. First, as a technique related to a semiconductor mounting structure or method using self-alignment, for example, a technique related to an electrode pattern, there is a technique described in JP-A-9-275123 and JP-A-11-111171. can give. For example, in Japanese Patent Application Laid-Open No. 11-111771, in consideration of positional deviation of a CSP carrier substrate by a mounting machine, electrode pads at four corners are larger than other electrode pads, and solder bumps at four corners are other solders. By mounting the CSP using the CSP carrier substrate and the wiring substrate formed larger than the bumps, the self-alignment of the solder bumps at the four corners at the time of reflow soldering is ideal for the carrier substrate and the wiring substrate. A structure in which a large misalignment from the mounting position is corrected and the self-alignment effect is improved by self-alignment of solder bumps other than the solder bumps at the four corners is shown.
[0004]
Further, as a mounting technique that improves the horizontal and vertical precision of the optical element by using self-alignment, for example, techniques described in Japanese Patent Application Laid-Open Nos. 5-60952 and 7-235666 are cited. For example, in JP-A-5-60952, in order to achieve horizontal positional accuracy of 1 micron or less by self-alignment, it is necessary to set the solder connection height to approximately 30 microns or higher, while in the vertical direction. In order to make the positional accuracy (the inclination of the optical element) 1 micron or less, it is necessary to make the solder connection height approximately 10 microns or less, and it is difficult to obtain a solder connection height that can satisfy both simultaneously. It has been shown. As a means for solving this problem, Japanese Patent Laid-Open No. 5-60952 discloses that a substrate side electrode in an indented groove formed using a non-conductive film and an electrode of an optical element are connected with solder, and a horizontal positioning solder is used. It has been shown to be achieved by self-alignment by surface tension, and vertical positioning is achieved by supporting on a pedestal with a non-conductive film.
[0005]
[Problems to be solved by the invention]
In the above prior art, the self-alignment effect is improved by forming the electrode pads at the four corners larger than the other electrode pads and the solder bumps at the four corners larger and higher than the other solder bumps. However, with such an electrode pattern and the amount of solder, there is a problem that it is difficult to ensure vertical positioning accuracy.
In addition, the conventional technique requires a non-conductive film patterning process and a positioning table forming process to ensure vertical positioning accuracy, and the substrate manufacturing process is complicated and expensive. .
[0006]
An object of the present invention is to provide a mounting structure technique for an optical element that solves the above-described drawbacks and realizes high-precision positioning in the horizontal and vertical directions only by the surface tension of molten solder.
Another object of the present invention is to provide an optical element mounting structure technique that achieves vertical positioning accuracy and high self-alignment by optimizing the electrode shape and the amount of solder.
[0007]
[Means for Solving the Problems]
In order to achieve the object of the present invention, in the first invention, the mounting structure of the optical element includes an electrode formed on the optical element and an electrode formed at a position corresponding to the electrode of the optical element on the substrate. Is a mounting structure for an optical element that uses solder to connect a first solder connection electrode provided in the vicinity of the periphery of the optical element, and a second solder disposed in another part of the optical element. If the electrode area S1 of the first solder connection electrode and the electrode area S2 of the second solder connection electrode are provided, S1> S2 is satisfied, and the first solder connection electrode is provided. H1 <H2 is satisfied, where H1 is the average solder height and H2 is the average solder height of the second solder connection electrode.
[0008]
According to a second invention, in the first invention, the electrode width of the first solder connection electrode is L1, the electrode interval between the first solder connection electrode and the second solder connection electrode is L12, When the electrode interval between the solder connecting electrodes is L22, the relationship of L1 / 2 <L12 and L1 / 2 <L22 is satisfied.
[0009]
In the third invention, an optical element mounting method includes mounting an optical element in which an electrode formed on the optical element and an electrode formed at a position corresponding to the electrode of the optical element on the substrate are connected using solder. In order to obtain a structure, a first solder connection electrode having a first area is provided in the vicinity of the periphery of the optical element, and a second area having an area smaller than the first area is provided in another part of the optical element. Providing a solder connection electrode; providing a first solder connection electrode and a second solder connection electrode at a position of the substrate corresponding to the electrode of the optical element; and the first of the optical element. Supply to the second solder connection electrode of the optical element or the second solder connection electrode of the substrate from the average solder height supplied to the solder connection electrode or the first solder connection electrode of the substrate Supplying solder so that the average solder height is high The optical element is positioned on the substrate at a predetermined position and temporarily connected at a temperature below the melting point of the solder while pressing, and the surface tension of the solder melted by heating above the melting point of the solder is used. And three-dimensional positioning of the electrode on the optical element with respect to the substrate electrode.
[0010]
In a fourth invention, in the third invention, in the step of providing the solder connection electrode, the electrode width of the first solder connection electrode is L1, and the first solder connection electrode and the second solder connection are provided. When the electrode interval between the electrodes for electrode is L12 and the electrode interval between the second solder connecting electrodes is L22, the relationship of L1 / 2 <L12 and L1 / 2 <L22 is satisfied.
[0011]
In a fifth invention, in the third or fourth invention, in the third or fourth invention, in the step of supplying the solder, when the width of the solder supplied to the first solder connection electrode on the optical element or the substrate is L3, 1 is L1> L3, and the relationship between the solder width L4 supplied to the second solder connection electrode and the second solder connection electrode width L2 is L2 ≦ L4. The solder is supplied so that the relationship between the solder height H3 supplied to the first solder connection electrode and the solder height H4 supplied to the second solder connection electrode satisfies H3 ≧ H4.
[0012]
According to a sixth invention, in the third, fourth, or fifth invention, the step of three-dimensional positioning with respect to the electrode on the substrate using the surface tension of the solder heated to the melting point of the solder or higher is reduced. Perform in a sex atmosphere.
[0013]
According to a seventh invention, in the third, fourth, or fifth invention, a step of supplying an organic material having a boiling point higher than the melting point of solder to the solder connecting electrode between the temporarily connected optical element and the substrate is provided.
[0014]
Furthermore, in the eighth invention according to any one of the above inventions, the method of supplying solder to the optical element or the electrode on the substrate is vacuum deposition.
[0015]
In a ninth aspect based on the seventh aspect, the organic material has at least one hydroxyl group in the molecule. The organic material evaporates after the solder connection step so that no residue remains.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings using examples. As an electrode material of the optical element mounting structure, for example, an electrode is formed on the substrate and the optical element with a structure of Ti, Pt, and Au. A crystal composition (Au 80 wt%, Sn 20 wt%) is generally used. The object of the present invention is applicable to the case of using these electrodes as well as other electrodes and solder materials.
[0017]
FIG. 1 is a plan view showing one embodiment of an electrode arrangement for solder connection of an optical element according to the present invention and a cross-sectional view showing one embodiment of a mounting structure of the optical element. FIG. FIG. 1B is a cross-sectional view of the mounting structure of the optical element, and FIG. As shown in FIG. 1A, the optical element 1 includes a circular first solder connection electrode 3a having a large electrode area S1 and a circular second solder connection having an electrode area S2 smaller than the electrode area S1. An electrode 3b is provided. The first solder connection electrodes 2a are provided at the four corners of the optical element 1, and the second solder connection electrodes 3b are disposed at other portions.
As shown in FIG. 1B, the substrate 5 is also provided with electrodes at positions corresponding to the electrodes of the optical element 1. The first solder connection electrode 2b of the substrate 5 is located at a position facing the first solder connection electrode 2a of the optical element 1, and the second solder connection of the substrate 5 is located at a position facing the second connection electrode 3a. A working electrode 3b is provided. The optical element mounting structure 101 connects the first and second solder connection electrodes 2 a and 3 a of the optical element 1 and the first and second solder connection electrodes 2 b and 3 b of the substrate 5 with solder 4. ing.
[0018]
In this embodiment, the optical element 1 is temporarily fixed on the substrate 5, that is, the electrode of the optical element is placed on the electrode on the substrate at a temperature lower than the melting point of the solder. For this purpose, a first solder connection electrode 2 having an electrode area S1 and a second solder connection electrode 3 having a smaller electrode area S2 are provided. In this embodiment, the first,
The second solder connection electrodes 2 and 3 are circular, but are not necessarily circular, and may be square, polygonal, or other shapes.
The second solder connection electrodes 3a and 3b are combined with the first solder connection electrodes 2a and 2b to ensure the connection strength, and the electrode pattern of the optical element 1 is only the first solder connection electrodes 2a and 2b. Compared with the case of, it is a small circular electrode provided in order to exhibit the self-alignment effect by the surface tension of solder more effectively.
[0019]
In addition, as shown in FIG. 1A, in order to prevent temporary fixing or connection on the adjacent electrode and realize high-accuracy positioning by self-alignment more effectively, the first of the optical element 1 is used. The electrode width of the solder connection electrode 2a is L1, the distance between the first solder connection electrode 2a and the second solder connection electrode 3a is L12, and the distance between the second solder connection electrodes 3a is L2. The electrodes 2a and 3a are arranged so that the relationship of L1 / 2 <L12 and L1 / 2 <L22 is established, where L22 is the electrode interval. For this reason, by using the optical element 1 provided with the first solder connection electrode 2a and the second solder connection electrode 3a, a large positional deviation is allowed at the time of temporary fixing, and high horizontal accuracy by self-alignment is achieved. Can be achieved.
[0020]
FIG. 1B uses the substrate 5 and the optical element 1 in which the first solder connection electrode 2b and the second solder connection electrode 3b are provided at positions corresponding to the electrode patterns 2a and 3a of the optical element 1. The optical element mounting structure 101 after soldering and self-alignment is shown.
In the present embodiment, the average solder height H1 of the first solder connection electrodes 2a and 2b formed in the peripheral portion is made lower than the average solder height H2 of the second solder connection electrodes 3a and 3b. As a result, the solder 4 melted in the vertical direction exerts a tensile force on the optical element 1 at the first solder connection electrode 2b, and a push-up force acts on the second solder connection electrode 3b. For this reason, a force that pushes up the optical element 1 in the central portion works, while a force that pulls the optical device 1 in the direction of the substrate 5 occurs in the peripheral portion. Even when the supplied solder amount varies due to the balance between the tensile force and the compressive force of the molten solder 4, the vertical accuracy of the optical element can be stabilized. In this case, as shown in FIG. 1B, the end portion of the solder 4a between the first solder connection electrodes 2a and 2b is recessed inward, and the solder 4b between the second solder connection electrodes 3a and 3b. Becomes convex outward.
[0021]
On the other hand, when the average solder height between the first solder connection electrodes 2a and 2b and the second solder connection electrodes 3a and 3b is equal, as shown in FIG. It was confirmed that tilting occurred due to only the force that pushes up the optical element 1 on the electrode, and vertical mounting accuracy might not be obtained. In order to eliminate this inclination, as shown in FIG. 2B, it is conceivable to bond the optical element 1 to the non-conductive film 15, but this is not preferable because the number of steps increases. FIG. 2 is a cross-sectional view of a conventional optical element mounting structure.
[0022]
Here, the average solder height will be described. The average solder height is equal to the volume of the solder supplied on the electrode of the substrate 4 by forming the electrode on the optical element 1 side and the electrode on the substrate 5 side as upper and lower surfaces and connecting the outer shape with a straight line. Says the height of the three-dimensional. That is, the average solder height is a value obtained by dividing the solder volume supplied to the solder connection electrode by the electrode area.
[0023]
FIG. 3 is a plan view showing another embodiment of the electrode arrangement for solder connection of the optical element according to the present invention. FIG. 3 (a) shows an example in which the shape of the electrode is a square, and FIG. FIG. 3C shows another arrangement example of the circular electrode and the small area circular electrode, and FIG. 3C shows another arrangement example of the large area square electrode and the small area square electrode.
FIG. 3A shows an example in which the first solder connection electrode 2a on the optical element 1 is rectangular and the second solder connection electrode 3a is rectangular. In FIG. 3 (b), the circular first solder connection electrodes 2a are not arranged at the four corners of the optical element 1, but are provided in the vicinity of the periphery of the optical element 1, and with respect to the center (center of gravity). An example of point symmetry is shown. In FIG. 3C, the square first solder connection electrodes 2a are not arranged at the four corners of the optical element 1, but are provided in the vicinity of the periphery of the optical element 1, and the center (center of gravity) is provided. An example of point symmetry is shown. In order to stabilize the posture of the optical element 1, the first solder connection electrode 2a and the second solder connection electrode 3a are arranged so as to be symmetric with respect to the center (center of gravity) of the optical element 1. It is desirable to do.
[0024]
FIG. 4 is a cross-sectional view showing another example of the mounting structure of the optical element according to the present invention. FIG. 4A shows the second solder connection of the substrate to the second solder connection electrode of the optical element. FIG. 4B shows an example in which the second solder connection electrode of the substrate is made larger than the second solder connection electrode of the optical element.
In FIG. 4A, the second solder connection electrode 2d on the substrate 5 side is provided small with the center of the electrode being symmetrical with respect to the second solder connection electrode 2c on the optical element 1 side. An optical element mounting structure 102 on which the optical element 1 is mounted is shown.
In FIG. 4B, the second solder connection electrode 2e on the optical element 1 side is provided so as to be symmetric with respect to the second solder connection electrode 2f on the substrate 5 side. An optical element mounting structure 103 on which the optical element 1 is mounted is shown. In this embodiment, the posture can be stabilized.
[0025]
FIG. 5 is a cross-sectional view for explaining one embodiment of the mounting process of the optical element mounting structure according to the present invention.
First, as shown in FIG. 5A, the solder 6 is supplied to the first solder connection electrode 2b and the second solder connection electrode 3c on the substrate 5. In this embodiment, reference numeral 6 is assigned to the solder before reflow to distinguish it from the solder 4 after reflow. Here, the relationship between the solder width L3 supplied to the first solder connection electrode 2b and the electrode width L1 is L1> L3, and the solder width L4 supplied to the second solder connection electrode 3b and the electrode width L2 The solder 6 is supplied so that the relationship is L2 ≦ L4, and the relationship between the average solder height H1 on the first solder connection electrode 2b and the average solder height H2 on the second solder connection electrode 3b is H1 <H2. In addition, in order to prevent any electrode of the optical element 1 from being temporarily fixed or connected to the solder 6 of the adjacent electrode, the solder height H3 supplied to the first solder connection electrode 2b of the substrate 5; It is desirable to supply the solder 6 such that H3 ≧ H4 within a range where the relationship of the solder height H4 supplied to the second solder connection electrode 3b satisfies the relationship of H1 <H2. The solder 6 can be supplied by vapor deposition, plating, preform, or the like. In the present invention, the solder 6 may be supplied by any method.
[0026]
Next, as shown in FIG. 5B, the optical element 1 having the first solder connection electrode 2a and the second solder connection electrode 3a is aligned on the substrate 5, and the supplied solder 6 Temporary connection is performed by applying pressure at a temperature below the melting point. Thereby, the position shift from the alignment to the main connection process due to the heating and melting of the solder 6 in the next process is prevented, and a mounting process with excellent productivity is realized.
Next, in order to realize high-accuracy positioning of the optical element 1 by self-alignment using the surface tension at the time of solder melting connection, the oxide film on the solder surface is removed at the time of solder melting or thin enough not to hinder self-alignment. Need to control. In this embodiment, as shown in FIGS. 5C, 5D, and 5E, the first solder connection electrodes 2a and 2b are self-melted by heating and melting in a reducing atmosphere 7. The amount of misalignment is reduced by the alignment effect, and then high-accuracy positioning can be realized by the self-alignment effect by the second solder connection electrodes 3a and 3b.
Thereafter, by cooling and solidifying the solder 4, as shown in FIG. 5 (f), since no flux is used, there is no residue affecting reliability, and a clean mounting structure that does not require a post-cleaning step Can be obtained.
[0027]
In the present invention, as a method of reducing the oxide film at the time of melting and heating the solder 6, there is a method using an organic material 8 having reducibility as shown in FIG. 6 in addition to heat printing in a reducing atmosphere 7 shown in FIG. 5. is there.
FIG. 6 is a sectional view for explaining another embodiment of the mounting process of the optical element mounting structure according to the present invention. As shown in FIG. 6A, the solder 4 is supplied onto the first solder connection electrode 2b and the second solder connection electrode 3b of the substrate 5, and as shown in FIG. The optical element 1 is placed on and temporarily fixed.
Next, as shown in FIG. 6C, an organic material 8 is supplied so as to cover the solder connection electrodes 2 a, 2 b, 3 a, 3 b between the optical element 1 and the substrate 5. As the organic material 8, a material having a boiling point higher than the melting point of the solder 6 and a state in which the oxide film on the solder surface is reduced and removed to prevent reoxidation when the solder is melted is selected. As the reducing material, an alcohol-based material having at least one hydroxyl group in the molecule is suitable. For example, when an Au 20 wt% Sn solder having a melting point of 278 ° C. is used, triethylene glycol (boiling point 285 ° C.), tetraethylene glycol (boiling point 314 ° C.), or pentaethylene glycol (boiling point 370 ° C.) is used as the organic material 8. Thus, it was confirmed that self-alignment is not hindered and high-precision positioning and mounting of the optical element 1 on the substrate 5 can be realized. As shown in FIGS. 6C, 6D, and 6E, when the organic material 8 is supplied or heated while being applied, the self-alignment effect of the first solder connection electrodes 2a and 2b is achieved. As a result, the amount of misalignment is reduced, and then high-accuracy positioning can be realized by the self-alignment effect by the second solder connection electrodes 3a and 3b. The organic material 8 is evaporated during heating. Therefore, the organic material 8 evaporates during heating as shown in FIG. 6 (f), so that it does not remain as a residue and a post-cleaning step is not required as in the above embodiment. That is, it is necessary to use a material having a lower boiling point and to evaporate surely as the heating rate increases and the heating time decreases.
[0028]
FIG. 7 is a partial cross-sectional side view and a plan view showing an embodiment when the optical element mounting structure according to the present invention is mounted on an optical waveguide substrate. The optical element 1 has an active layer 10, and the first and second solder connection electrodes 2 a and 3 a are mounted on the electrodes 2 b and 3 b of the optical waveguide substrate 13. The optical waveguide 11 is attached to the optical waveguide substrate 13 so that the light that has passed through the active layer 10 of the optical element 1 can pass through the core layer 12 of the optical waveguide 11.
By using this embodiment, a mounting structure in which the optical element 1 is positioned at a predetermined position on the substrate 5 with high accuracy can be realized. For this reason, the core layer 12 and the active layer 10 of the optical element 1 can be positioned with high accuracy in the optical waveguide 11 on the substrate 5, and optical coupling between the optical element and the optical waveguide can be realized.
[0029]
As described above, according to the present invention, without using a flux, a vertical positioning support base, and an expensive mounting machine, only the self-alignment effect due to the surface tension at the time of melting of the solder can be used. The optical element can be positioned with high accuracy, and the cost can be reduced.
[0030]
【The invention's effect】
As described above, according to the present invention, the optical element can be accurately positioned at a predetermined position on the substrate by the self-alignment effect due to the surface tension at the time of melting the solder.
[Brief description of the drawings]
FIG. 1 is a plan view showing an embodiment of an electrode arrangement for solder connection of an optical element according to the present invention and a cross-sectional view showing an embodiment of an optical element mounting structure.
FIG. 2 is a cross-sectional view of a conventional optical element mounting structure.
FIG. 3 is a plan view showing another embodiment of the arrangement of electrodes for solder connection of the optical element according to the present invention.
FIG. 4 is a cross-sectional view showing another example of an optical element mounting structure according to the present invention.
FIG. 5 is a cross-sectional view for explaining an embodiment of the mounting process of the optical element mounting structure according to the present invention.
FIG. 6 is a cross-sectional view for explaining another embodiment of the mounting process of the optical element mounting structure according to the present invention.
FIGS. 7A and 7B are a partial cross-sectional side view and a plan view showing an embodiment in which an optical element mounting structure according to the present invention is mounted on an optical waveguide substrate. FIGS.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical element, 2a, 2b ... 1st solder connection electrode, 3a, 3b ... 2nd solder connection electrode, 4 ... Solder after reflow, 5 ... Board | substrate, 6 ... Solder before reflow, 7 ... Reduction 8 ... Organic material, 10 ... Active layer, 11 ... Optical waveguide, 12 ... Core layer of optical waveguide, 13 ... Optical waveguide substrate 101, 102, 103 ... Optical element mounting structure.

Claims (4)

光素子上に形成された電極と基板上の光素子の電極に対応する位置に形成された電極とをはんだを用いて接続する光素子の実装構造体を得るために、該光素子の周辺近傍に第１の面積を持つ第１のはんだ接続用電極を設け、光素子の他の部分に該第１の面積より小さい面積を持つ第２のはんだ接続用電極を設けるステップと、
該光素子の電極に対応する該基板の位置に第１のはんだ接続用電極と第２のはんだ接続用電極を設けるステップと、
該光素子の該第１のはんだ接続用電極又は該基板の該第１のはんだ接続用電極に供給する平均はんだ高さより、該光素子の該第２のはんだ接続用電極又は該基板の該第２のはんだ接続用電極に供給する平均はんだ高さが高くなるようにはんだを供給するステップと、
該基板上に該光素子を所定の位置に位置合わせを行い加圧しながらはんだの融点以下の温度で仮接続するステップと、
はんだの融点以上に加熱して溶融したはんだの表面張力を利用して該基板電極に対する該光素子上電極の３次元的な位置決めを行うステップとを有し、
該はんだを供給するステップは、該光素子または基板上の該第１のはんだ接続用電極に供給するはんだ幅をＬ３とした場合、該第１のはんだ接続用電極幅Ｌ１との関係がＬ１＞Ｌ３となり、かつ該第２のはんだ接続用電極に供給するはんだ幅Ｌ４と該第２のはんだ接続用電極幅Ｌ２との関係がＬ２≦Ｌ４となり、かつ、該第１のはんだ接続用電極に供給するはんだ高さＨ３と該第２のはんだ接続用電極に供給するはんだ高さＨ４の関係がＨ３≧Ｈ４となるようにはんだを供給することを特徴とする光素子の実装方法。In order to obtain a mounting structure of an optical element for connecting an electrode formed on the optical element and an electrode formed at a position corresponding to the electrode of the optical element on the substrate using solder, in the vicinity of the periphery of the optical element Providing a first solder connection electrode having a first area and providing a second solder connection electrode having an area smaller than the first area in the other part of the optical element;
Providing a first solder connection electrode and a second solder connection electrode at a position of the substrate corresponding to the electrode of the optical element;
From the average solder height supplied to the first solder connection electrode of the optical element or the first solder connection electrode of the substrate, the second solder connection electrode of the optical element or the first of the substrate Supplying the solder so that the average solder height supplied to the solder connecting electrode of 2 is increased;
Temporarily connecting the optical element on the substrate at a predetermined position at a temperature below the melting point of the solder while applying pressure;
Performing three-dimensional positioning of the electrode on the optical element with respect to the substrate electrode using the surface tension of the solder heated to the melting point of the solder or higher ,
In the step of supplying the solder, when the solder width supplied to the first solder connection electrode on the optical element or the substrate is L3, the relationship with the first solder connection electrode width L1 is L1>. L3, and the relationship between the solder width L4 supplied to the second solder connection electrode and the second solder connection electrode width L2 is L2 ≦ L4, and the supply to the first solder connection electrode implementation of the optical element characterized that you supply the solder so that the relation of the solder height H3 and the second solder connection for supplying to the electrode solder height H4 is H3 ≧ H4 to. 請求項１記載の光素子の実装方法において、
該はんだ接続用電極を設けるステップでは、該第１のはんだ接続用電極の電極幅をＬ１、該第１のはんだ接続用電極と第２のはんだ接続用電極の電極間隔をＬ１２、第２のはんだ接続用電極間の電極間隔をＬ２２とした場合、Ｌ１／２＜Ｌ１２、かつＬ１／２＜Ｌ２２の関係を満足させることを特徴とする光素子の実装方法。In the mounting method of the optical element of Claim 1 ,
In the step of providing the solder connection electrode, the electrode width of the first solder connection electrode is L1, the electrode interval between the first solder connection electrode and the second solder connection electrode is L12, and the second solder An optical element mounting method characterized by satisfying a relationship of L1 / 2 <L12 and L1 / 2 <L22 when an electrode interval between connection electrodes is L22. 請求項１又は２に記載の光素子の実装方法において、
該はんだ融点以上に加熱して溶融したはんだの表面張力を利用して該基板上電極に対する３次元的な位置決めを行うステップを、還元性雰囲気の中で行うことを特徴とする光素子の実装方法。In the mounting method of the optical element of Claim 1 or 2 ,
A method for mounting an optical element, wherein the step of performing three-dimensional positioning with respect to the electrode on the substrate using the surface tension of the solder heated to the melting point of the solder or higher is performed in a reducing atmosphere. . 請求項１又は２に記載の光素子の実装方法において、
仮接続した該光素子と該基板間のはんだ接続用電極にはんだの融点よりも高い沸点を有する有機材料を供給するステップを設けることを特徴とする光素子の実装方法。In the mounting method of the optical element of Claim 1 or 2 ,
A method for mounting an optical element, comprising the step of supplying an organic material having a boiling point higher than the melting point of solder to the temporarily connected optical element and the solder connection electrode between the substrates.
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